1. Field of the Invention
The invention relates generally to coexisting designs of multiple radio modules in a wireless communication device, and more particularly to an activity coordination method for coordinating the operations of the multiple radio modules such that interference between the multiple radio modules may be efficiently reduced while saving power.
2. Description of the Related Art
The Institute of Electrical and Electronics Engineers (IEEE) has adopted a series of standards for both Wireless Local Area Networks (WLANs) known as 802.11 and Wireless Metropolitan Area Networks (WMANs) known as 802.16. It is commonly known that Wireless Fidelity (WiFi) refers to interoperable implementations of the IEEE 802.11 technology, and Worldwide Interoperability for Microwave Access (WiMAX) refers to interoperable implementations of the IEEE 802.16 technology. On the other hand, Bluetooth (BT) is a wireless standard for Wireless Personal Area Networks (WPANs) developed by the BT special interest group (SIG). BT provides a secure way for exchanging data over short distances using frequency-hopping spread spectrum technology. Due to scarce radio spectrum resource, different technologies are allowed to operate in overlapping or adjacent radio spectrums. For example, WiFi often operates at 2.412-2.4835 GHz, WiMAX often operates at 2.3-2.4 or 2.496-2.690 GHz, and BT often operates at 2.402-2.480 GHz.
As the demand for wireless communication continues to increase, wireless communication devices such as cellular telephones, Personal Digital Assistants (PDAs), laptop computers, etc., are increasingly being equipped with multiple radios. A Multiple Radio Terminal (MRT) may simultaneously include BT, WiMAX, and WiFi radios. Simultaneous operation of multiple radio modules co-located on the same physical device, however, can suffer from significant degradation including significant interference therebetween because of the overlapping or adjacent radio spectrums. Due to physical proximity and radio power leakage, when the data transmission of a first radio module overlaps with the data reception of a second radio module in the same time domain, the data reception of the second radio module can be hindered due to interference from the data transmission of the first radio module. Likewise, data transmission of the second radio module can interfere with data reception of the first radio module.
FIG. 1 is a schematic diagram illustrating interference between a Mobile Wireless System (MWS) radio module 11 and a BT master radio module 12 that are co-located in an MRT. Both of the MWS radio module 11 and the BT master radio module 12 transmit and receive data via scheduled transmitting (TX) and receiving (RX) time slots on a frame-by-frame basis. For example, in each MWS frame, the first five consecutive RX slots are scheduled for receiving operations and the three consecutive TX slots are scheduled for transmitting operations. Due to the fact that the MWS radio module 11 and the BT master radio module 12 are co-located within the MRT 10, the transmission of one radio module will generally interfere with the reception of another radio module. As shown in FIG. 1, data receptions in the three RX time slots of the BT master radio module 12 are interfered by concurrent data transmissions in TX time slots of the MWS radio module 11, and data receptions in the six RX time slots of the MWS radio module 11 are interfered by concurrent data transmissions in TX time slots of the BT master radio module 12.
FIG. 2 is a schematic diagram illustrating traffic patterns of a BT master radio module 22 affected by a co-located MWS radio module 21. The traffic pattern of the MWS radio module 21 remains the same as the traffic pattern of the MWS radio module 11 in FIG. 1, while the BT master radio module 22 has an Extended Voice (EV3) traffic pattern using an Extended Synchronous Connection Oriented (eSCO) link with TeSCO=6 and WeSCO=4. Under such EV3 traffic pattern, the BT master radio module 22 has one scheduled TX time slot followed by one scheduled RX time slot for every six BT slots (i.e., TeSCO=6), and has four retransmission opportunities (i.e., WeSCO=4). Note that, in the example of FIG. 2, the BT master radio module 22 uses low transmission power, so that the data transmissions of the BT master radio module 22 does not interfere with the data receptions of the MWS radio module 21, but the data transmissions of the MWS radio module 21 interferes with the data receptions of the BT master radio module 22. Specifically, in eSCO window #2, the EV3 data reception in the first scheduled EV3 RX time slot is corrupted by the concurrent data transmission of the MWS radio module 21, causing the BT master radio module 22 to re-transmit the EV3 data to a BT slave in the following EV3 TX time slot and to receive EV3 data from the BT slave in the following EV3 RX time slot. For such a case, it is obvious that the BT master radio module 22 needs to consume 25% more power due to interference from the co-located MWS radio module 21.